The long-term goal of this project is to develop a safe, efficient gene transfer technology that can be used for gene therapy of diseases in the colorectal system. The R21 phase of this project will focus on the development of a gene transfer technology that allows safe, efficient, and focused delivery of transgenes to the colorectal system. During this technology development phase, we will use inflammatory bowel disease (IBD), which consists of Crohn's disease and ulcerative colitis, as a first target to assess the efficacy of the gene transfer technology. We have recently developed a novel gene transfer technology, in which viral particles (adenoviral vectors and adeno-associated viral vectors) are delivered to target sites in a microbead-associated form. These virus-microbead conjugates can infect target cells at efficiencies much greater than the same viral vectors used free in solution. A key feature of this gene transfer technology is that the infection sites by viral vectors are equal to the contact sites between target cells and virus-microbead conjugates. This allows focused delivery of transgenes to target sites with high transduction efficiencies by placing virus-microbead conjugates at the site of interest. Since each viral particle on the microbeads either mediates infection of a cell or stays on the microbeads, no free viral particles should be present. Thus, uncontrolled transduction of other non-target tissues or organs by viral vectors can be eliminated, and immune responses to viral vectors can be minimized. These and other characteristics suggest that this technology could allow for the efficient, safe delivery of transgenes to the colorectal system. In particular, it could be very useful for the development of effective gene therapy protocols for IBD, since a potentially efficacious gene therapy strategy for IBD is to repress intense inflammation in the colon by local, high-level expression of anti-inflammatory cytokines at inflamed lesions. We will investigate the potential of this gene transfer technology for the safe, focused delivery of the gene for a potent anti-inflammatory cytokine, interleukin-10 (IL-10), to inflamed lesions in the colon for the amelioration of established colitis. We hypothesize that this technology will allow for safe, efficient, and focused delivery of the IL-10 gene to inflamed lesions in the colon, resulting in the local expression and secretion of IL-10 in the inflamed lesions for the amelioration of established colitis with minimal detrimental effects on other tissues and organs.